feat(mp): AI 聊天传递 patient_id 支持体征数据查询 Tool Call

- ai-chat service: sendAiMessage 新增 patientId 可选参数
- messages 页面: 从 authStore 获取 currentPatient.id 传入

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/miniprogram/src/services/ai-chat.ts

@@ -16,11 +16,16 @@ export interface AiChatResponse {
 export async function sendAiMessage(
   message: string,
   history?: AiChatMessage[],
+  patientId?: string,
 ): Promise<AiChatResponse> {
-  const resp = await api.post<AiChatResponse>('/ai/chat', {
+  const body: Record<string, unknown> = {
     message,
     history: history?.slice(-10),
-  });
+  };
+  if (patientId) {
+    body.patient_id = patientId;
+  }
+  const resp = await api.post<AiChatResponse>('/ai/chat', body);
   return resp;
 }